CORRESPONDENCE.
The R.A.F. and the Industry.
11833] It is certainly about time this heated question was settled ;
and tne first matter is to define the position and to state exactly what
is wrong. People talk of the industry as if the various firms were
one and all absolutely similar, but such is far from being the case. «
They are divided roughly between the two extremes of what one
might term the " Designers" and those who build to R.A.F.
designs, i.e., the " Designees."
Mr. Walton Newbold, in his new book " The War Trusts
Exposed," condemns the present policy of the country paying for the
upkeep of the R.A.F. for the benefit of the private industry, i.e.,
those whom I term the " Designees." Naturally those at the
other end, i.e., the " Designers," do not want the R.A.F. at all,
and so on with the various grades between these two extremes.
The present complication has arisen because there has never been
a clear and definite statement as to the official R.A.F. policy. Is
the R.A.F. to design and incidentally to guard the country's
interests in the purchase of aeroplanes, or is its position to be that of
technical expert to the War Office and, incidentally, to carry out
experimental work ? Again, are we to look to it at all for the supply
of our machines ?
The R.A.F. appears to be doing a bit of everything, which
always proves fatal, for it invariably ends up in no job being
satisfactorily performed.
If we want to encourage the very best in aeroplanes, most people
will be agreed that we must buy in the open market. Nobody can
object to the Government having a body of technic?l experts to
attend to this buying, and the R.A.F. are quite able to see to this ;
but if the R. A.F. is to have the slightest control in the buying, then
they must not design or make aeroplanes. I cannot imagine any
man, or body of men, so wanting in human nature that they did
not consider their own production to be the best. If I were a
designer and entered my design in a competition, I would think you
very foolish indeed to make me the judge.
I think the above sums up the position, and has the advantage of
leaving out the unnecessary trimmings.
If the War Office will thoroughly overhaul and rearrange the
present constitution of the R.A.F. and its duties without any further
delay, it would bring this very unpleasant feeling to an end before it
becomes very much worse.
February 3rd. " OCTOPUS,"
Stability of Aeroplanes.
[1834]. I have been reading with very great interest in your
valuablel journal the paper by Mr. Bairstow and the discussion on it,
and it seems to me that Mr. Bairstow's definitions of stability are about
the best yet evolved. I do not understand even yet why inherent
stability is not preferable to automatic stability. In the former the
self-righting qualities are " the nature of the beast," and contrary
to popular superstition, not detrimental to its controllability; in
the latter they depend on some mechanically operated device and
will disappear if the device breaks down.
Mr. Bairstow apparently favours inherent stability, but he sets
out to obtain it by the use of fins and deep bodywork, if I under
stand him aright. But, if the functions of the fins, &c, can be
fulfilled with less than their weight and resistance, then they are
unnecessary, and I suggest that it would be best to use the Dunne
V form of wings with down-rolled front edges at the tips, or some
equivalent form. This type needs no tail, and no more bodywork
than a Farman-type biplane. The Dunne machine from all accounts
entirely satisfies the definition of inherent stability. It has made
many uncontrolled flights; two, a straight and a circular one of
about 1 min. duration each, if I remember rightly, under R.Ae.C.
observation ; another in which the pilot wrote a sentence on a piece of
paper, leaving the machine to run its own course, and then the flight
at Hendon, when Com. Felix tinkered with the engine. Another
advantage is that it is a propeller machine, not a tractor like the
H.P. or Etnch types, and so is much better suited for military
purposes. Also, I believe that the Dunne principles of stability as
applied in that machine are, unlike those of the H.P. type, not
conducive to, and do not involve, any rolling to speak of, even in
fatrly gusty winds. Then there is the bogey of uncontrollability to
be laid. People often think that a Dunne for instance cannot
manoeuvre so well as, say a Bleriot. But, though I have no
acquaintance with the Dunne machine except from what I have
seen published about it, the fact seems to be that it is particularly
easily controlled, however much the reasons assigned may be
contested. Most of the opinions regarding inherent stability that
I have read seem to show this prejudice about uncontrollability,
which practical experience demonstrates to be totally unfounded.
Experiments also show, and Mr. Dunne is reported to have stated
expressly before the Aeronautical Society, that his machine does not
roll when near the ground, so there is no need to " switch off" the
stable qualities when landing or taking off. When Com. Felix
left the controls locked for so long what prevented the machine
from playing all sorts of awkward and perhaps disastrous tricks but
its inherent stability ? If he had left the controls unlocked, it would
be like leaving a boat's tiller to bang about unlashed, which is not
good for it. The Dunne turns into the gusts if left alone and so
causes the sustentation to become equal under both wings. On
this account it can be accused of bad directional stability with,
regard to its compass course, and justly so. But this entails
no more mental labour than the steering of a boat by compass or
otherwise in a rough sea does. The analogy is quite correct,
because the Dunne cannot side-slip, &c, any more than a boat
can, though it does not roll about like a boat. As for efficiency,
which is the better : an efficient pair of wings dragging a large body
and tail, or a slightly less efficient pair without these encumbrances ?•
Again, I believe that the latter wings have been shown by experiment
to be no handicap. Practice shows that in the Dunne machine
the undeniable facts are : that it is not stiff or tricky in manoeuvring,
does not side-slip, nose dive, stall itself or pancake, and that it
does not roll when near the ground. What more does anyone
want but a reliable engine? I might add that Mr. Bairstow's
definition is satisfied completely by Dunne gliders cut from notepaper
with no bodywork, in calm and wind, and that they do not roll or
buck about in any way.
Apologising for trespassing on so much of your valuable space.
Dublin, February 2nd. W.F.G
Safety Aeroplanes.
[1835] With regard to the question of the dihedral system of
planes raised by your correspondent B2, letter No. 1820, I fail to
see that the reply thereto set out in letter No. 1831 is any argument
against the development of the pronounced dihedral angle.
The end losses referred to can easily be utilised with advantage,
as in the case of the finest inherent stability machines of the present
time where the pronounced dihedral is a leading feature, the wing
extremities being curved sightly downwards. It will be seen that
the upward deflection of the air means a uniform concentrated lift
at the plane ends; this I consider is of great importance to lhe
"even keel " theory. Furthermore, side gusts would tend to deflect
the windward wing, assisted, of course, by a low fuselage surface.
I also do not agree with your correspondent when he says that
" No well designed aeroplane will glide upside-down unless held so-
by the use of the controls by the pilot." Accidents of late have
proved that planes possessing little or no dihedral are quite capable
of landing gently on their backs, with or without the pilot on board.
Battersea, S.W., February 2nd. JOHN W. ROBINS.
A System for the Classification of Aeroplanes.
[1836] Although the science of aviation continues to make rapid
strides, the advent of a fixed system for the classification of aero
planes appears to be as far off as ever.
The object of any method of classification should be to produce a
system as comprehensive as possible with the least possible amount
of change in the terms in general use. It should take into considera
tion not only the forms at present in regular use, but also possible
changes which may arise in the future, which, if unprovided for,
would in due course break down the system.
The first classification of aeroplanes was naturally based on the
number of sustaining surfaces. Thus machines were divided into
monoplanes, biplanes, triplanes, &c. As the number of different
types increased, it was soon found necessary to subdivide these
divisions in order to make exact description easier.
One system adopted was limited to biplanes, and was based upon
the position of the screw by which the machine was driven—namely,
whether it was a " Propeller " or a " Tractor." This method is exceed
ingly weak, as it is possible to have machines practically identical in
construction driven by either tractors or propellers. For example,
the D'Artois biplane, which, whilst belonging to the " Tractor " type
of construction, must be classed as a " Propeller" biplane, as it is
driven by a propeller at the extreme tip of its tail. Now the
"Propeller" biplanes include the Henry and Maurice Farman
machines, which bear no resemblance whatever to the D'Artois
biplane, which obviously belongs to the same main type as the
Avro and Breguet. Again, the Caudron biplane, which falls
within the " Tractor" class, is of an entirely different type of
construction to the Sopwith and B.E. 2, which also belong to this
class. The inefficiency of this method of classification was shown,
when Messrs. Short Brothers produced a biplane driven by one
propeller and two tractors. This has resulted in the mere statement
that a machine is of the '' Tractor " type or " Propeller " type being
insufficient to convey an exact idea of its appearance without a
detailed description being added.
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